Domain Name System (DNS) network services are generally ubiquitous in IP-based networks. DNS tunneling is an approach used to convey messages through TCP tunnels over DNS protocol that is typically not blocked or monitored by security enforcement, such as firewalls.
As such, DNS tunneling can be utilized in many malicious ways that can compromise the security of a network. For example, DNS tunneling can be used for various malicious/unauthorized activities, such as data exfiltration, cyber-espionage, and/or command and control.